Diruthenium Tetracarbonate Trianion, [Ru^II/III₂(O₂CO)₄]³⁻, Based Molecule-Based Magnets: Three-Dimensional Network Structure and Two-Dimensional Magnetic Ordering

HxK1−xMII[Ru2(CO3)4](H2O)y(MeOH)z (M = Mn, Fe, Co, Ni, Mg) were synthesized from the reaction of MII and K3[Ru2(CO3)4] in water and are isomorphous with an orthorhombic three-dimensional network structures based on μ3-CO32− linkages to Ru2 moieties forming layers and also to trans-MII(OH2)4 sites forming linked chains that connect the layers. They, as well as non-isomorphous M = Cu, magnetically order as canted ferrimagnets with Tc = 4.4 ± 1.0 K. The presence of S = 0 MII = Mg(II) has essentially no effect on Tc suggesting that the main magnetic pathway does not occur the through MII-based chains, but only via Ru2···Ru2 linkages that reside in layers. This is a rare example of a magnet based upon a second row transition metal.